1. Technical Field
Embodiments of the present invention relate generally to image processing and, more particularly, to an information insertion method, an information extraction method, and an information extraction apparatus using dot-based information robust to geometric distortion.
2. Description of the Related Art
As the technical capabilities of companies improve, cases where high-tech industrial technologies are externally leaked continue to occur. The leakage of technology is chiefly performed by insiders who intelligently make bad use of the weak points of existing security systems.
Accordingly, there is a need for a technology that is capable of inserting barely perceptible or imperceptible information into a target, such as a printed confidential document or a monitor screen, and extracting the inserted information from the target when the target is externally divulged.
In relation to the insertion of information into a target, there is a method of inserting information into a target by controlling the location and direction of a dot pattern inserted into the target. A related technology using this method includes Korean Patent No. 10-0906457 entitled “Information Input/Output Method Using Dot Pattern.” In this technology, reference lattice lines are present on the surface of a medium in a vertical direction and a horizontal direction. A dot is disposed at a location that corresponds to a specific distance and direction for a virtual lattice dot, that is, the intersection of the reference lattice lines, and information is inserted into the location. In other words, the distance and direction of a dot for a virtual lattice dot represents information. However, this technology is problematic in that it requires a reference lattice dot for indicating a reference lattice line and it is not robust to various geometric modifications.
Another related technology regarding the insertion of information into a target includes Korean Patent No. 10-0403204 entitled “Method and Apparatus for Embedding and Extracting Watermark for Binary Text.” In this technology, a document is converted into a binary image, a line in which letters are written is detected in the binary image, and information is inserted by deforming information in the detected line. However, this method is problematic in that it is difficult to deform information in a line in an actual environment in which information is inserted and extracted and that the method is not robust to various geometric modifications.
As described above, the above related technologies have limitations on actually inserting meaningful information into a target and extracting meaningful information from a target.